Economicus wrote:
Hi! Is there a simple method to calculate ICC in Stata?
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-findit intraclass- brings up -loneway-, if that's what you're looking for.
A few years ago, I adapted Robert M. Hamer's SAS macro that provided for all of
the intraclass correlation coefficients (and their confidence intervals)
described in P. E. Shrout and J. L. Fleiss, Intraclass correlations: Uses in
assessing rater reliability. _Psychological Bulletin_ 86:420-428, 1979. It
worked for balanced datasets (it called -anova-) for all of the various ICCs,
and for unbalanced datasets (it called -xtreg-) one type of ICC. StataCorp's
rewrite of -anova- a while back broke it for some reason that I wasn't able to
uncover. Datasets in practice are rarely nicely balanced, so there hasn't been
much incentive to fix it.
When -xtmixed- is available, I plan go back and re-work it, and add the
additional ICCs described in K. O. McGraw and S. P. Wong, Forming inferences
about some intraclass correlation coefficients. _Psychological Methods_ 1:30-
46, 1996.
Joseph Coveney
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